Supercritical Carbon Dioxide Extraction of Sinensetin, Isosinensetin, and Rosmarinic Acid from Orthosiphon stamineus Leaves: Optimization and Modeling

Due to the health benefits such as anti-diabetic, antioxidant, and anti-inflammatory agents, the extraction of bioactive compounds from natural plants becomes significant. One of the favored extraction processes is supercritical carbon dioxide (SC-CO₂). SC-CO₂ is known as a green method with a high-selectivity process. Therefore, this study aims to determine the best parameters and mass transfer process to extract the bioactive compounds, viz. sinensetin, isosinensetin, and rosmarinic acid, in the leaves of Orthosiphon stamineus using the SC-CO₂ extraction technique. Response surface methodology was applied to optimize the operating temperature and pressure of 40–80 °C and 10–30 MPa, respectively. Meanwhile, to quantify the concentration of sinensetin, isosinensetin, and rosmarinic acid, a high-performance liquid chromatography was used. Results showed that the level of sinensetin, isosinensetin, and rosmarinic acid varied significantly at each extraction condition from 122.98 to 469.54 mg/kg sample, 50.60 to 419.07 mg/kg sample, and 17.43 to 931.44 mg/kg, respectively. Based on the optimization study, the optimum pressure and temperature were 10 MPa and 80 °C, respectively, with 440.3 mg/g sinensetin, 392.9 mg/g isosinensetin, and 752.0 mg/g of rosmarinic acid concentration obtained. Meanwhile, the single-sphere model showed a significant correlation with sinensetin, isosinensetin, and rosmarinic acid extraction, with an average AARD of 12.31%, 13.72%, and 18.90%, respectively. The range of diffusivity coefficient, D_e, of sinensetin, isosinensetin, and rosmarinic acid was 5.47E−13–1.81E−12 m²/s, 8.26E−13–1.89E−12 m²/s, and 2.64E−13–2.28E−12 m²/s, respectively.